Apparatus for working sheet metal



Sept. 6, 1949. s ANDERSON APPARATUS FOR WORKING SHEET METAL ll Shee'ts-Sheet 1 A Filed Feb. 19. 1942 INVENTOR. FoH/MA/ /I/veso/v ATTORNEY 1l Sheets-Sheet 2 Filed Feb. 19, 1942 INVENTOR. Fea/#MN AA/@EBJQM I ATTORNEY.

Sept. 6, 1949. F. ANDERSON APPARATUS FOR WORKING STIEET METAL 11 Sheets-Sheet 5 Filed Feb. 19, 1942 ATTORNEY.

F. ANDERSON APPARATUS FOR WORKING SHEET METAL Sept. 6, 1949.

11 Sheets-Sheet 4 Filed Feb. 19, 1942 fwxr H NNN NN w\ \N mm Sv N l N MJ .Dv mm., mmm wf. W w WN Z QM. L\ Wl Rf I N A ff H O om liltwnvwwunnvnlnmmmwuumm @www wm l Mw a NQ md WW NQ MQ ATTORNEY.

Sep; 6, N49. F. ANDERSON APPARATUS FOR WORKING SHEET METAL 11 Sheets-Sheet 5 Filed Feb. 19. 1942 RN. W ma m mw w mm m A Sept. 6, 1949. F. ANDERSON APPARATUS FOR WORKING SHEET METAL Filed Feb. 19, 1942 l1 Sheets-Sheet 6 Sept. 6, 1949. F. ANDERSON APPARATUS FOR WORKING SHEET METAL Filed Feb. 19, 1942 11 Sheets-Sheet '7 T E* M Mw ,MM4 w mw. A A Imm, M bw .ww wh wv M mh, E, f m mw l\ k n@ m l l 0 a.. Mn w E wh uw NE Y N h5 kum? mm MN\ NQ i l-m Sept. 6, 1949. F. ANDERSON APPARATUS FOR WORKING SHEET METAL 11\ Sheets-Sheet 8 Filed Feb. 19, 1942 INVENTOR. E60/,WAN /lA/QffJo/M l /dvU/- Aro/P/vfy Sept 6 1949 F. ANDESON 2,480,826

APPARATUS FOR WORKING SHEET-METAL Filed Feb. 19, 1942 l1 Sheets-Sheet 9 Sept 6, 1949- F. ANDERSON APPARATUS FOR WORKING' SHEET METAL ll Sheets-Sheet 10 Filed Feb. 19, 1942 5 mm H Ef 2 ww M W Tlf e H a K/J w w f 9/ ...E I4 3 SePt- 6, 1949 F. ANDERSON APPARATUS FOR WORKING SHEET METAL l1 Sheets-Sheet l1 Filed Feb. 19. 1942 l INVENTOR. @0f/NAN A/vf/aro/v BY Wn/l .ATTO/V/VEY Patented Sept. 6, `1941i) ED ES PATENT Y 4 2,480.83@ Y AEAEATUS. WORKING SHEEI Erohman Anderson, Brooklyn, N. Arnliraticnlehruary 19, 1942*?. erhl'la. lh

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ThisY application is in part a continuation of copending application Serial No. S17-,830, filed February 2, l9'40pnow U'. S. Batent 2,395,65-L

rIlie invention relates in general to the art of working sheetinetal tvo give it compound curvatures, and is particularly useful where the sheets to be worked are of such a size that a reciprocating press would not be practical for the purpose.

More particularly my invention relates to that class of sheet metalworking in which a sheet is pulled through engaging members that are @alculated to impart to the sheet a diierential lungi-.- tuolinal stretching. that isz a longitudinal stretchingv that varies in degree transversely or from one edge to the other. 1t is manifesty that such treatment of a sheet will impart to it a compound curvature depending upon the arnount and distribution of the stretching.y

It is characteristic of my invention that the en,- gaging .members are f different Shape and praduce Such a ir'ictional drag upon the .Sheet that the sheet is continuously dirnsnsifmaly distorted duri-ng its passage through the engaging bers proportionally to the difference distance betweenthe oacting engaging points or the two members.

The differential longitudinal stretching of any selected pattern williampart to a sheet a prede'- ter-mined changer-1 surface area will able the sheet to assume any of an infinite nurnber of related compound curvatures. the theoretical limits being an infinite radius of jlongitundiiial rcurvature coincident with a z ero radius of transverse curvature, and a zero radius of 'longitudinal curvature coincident with an ininite radius of transverse curvature. For each longitudinal curvature at any point there is one and only one transverse curvature.

The particular pair of principal curvatures that the sheet assumes at any Apoint depends upon the -net diierence Vin stretching of the sheet throughout 'its thickness at that point parallel t o its surfaces, and the invention contemplates con: trolling the differential stretching in thatdirnension. This latter control is particularly essential in connection with the drawing method that is 4characteristic of the invention" Specifically Ithe engaging members are slotted dies each having a Working edge over which the sheet is drawn and -upon which -suicien-t ldrag produced to effect the desired differential vlongitudinal stretching; Most simpiy-the invention is illustrated by two such dies, the -rear one-having, say, a straight-working edge and the Vadvance .die having a curved working edge. In order that the 32 Claims.

sheet on opposite` sides or-suraces Y It is obvious. that atv these sharp bends. the sheet is stretched unequally. throughut its thickness and there is effected in the sleet 'a net resul-t'of this unequal stretching which may v'produce a sheet with an undesirable shape even though the surface area is. correct. It is the differential stretching or the sheet throughout its thickness that the invention aims to control and-thereby determine the ultimate shape a sheet for. a vgiven dillerentiallongitudinal stretching. i A

The invention contemplates suitable means for eecting the results mentioned. Also the`invention involves the altering of the stretching'o the sheet in its various dimensions, either piogessively or steps, as the sheet is being drawn through the dies, andto this end either the ushape or relative location of the dies is susceptible' o'f change atwill.

In the drawings;-

Eig. 1 is a -plai view on a small scale diagrammatically showing the general arrangement of my apparatus;

Fig". 2y is a diagrammatic uside elevation on the same scale as 1;

Fig. 3 is aplan v ielvv partly broken avvay shoyving .the general arrangement 'f the various dies and operating mechanism therefor in one form of'my apparatus;

Iiig. 4 is a section taken longitudinally of the apparatus through the iirst die'sliovving `a modi'- ecl form of slot which may `Joe used to irripose an additional dragon the ahee'tas-it 4is pulled through the die;

Fig. 5 a transverse `section taken 'substantiallyon Athefline 5 5 of Eig. 3;,-

Fig. 6 isa fragmentary el'eyatiqna-l vieri( of .one portion of `the apparatusY as' yievvgred fr ogn a"p`osi tion indicated by the line (6 6 i ljig 3E" U 'n' Fig. is a dtail sectionaly vieyv ftaien on the une 1-1of Fig. 3;

Fig. 8 is a longitudinal section talrren substanf -tially on thelin of-eFi'g.

Eig. il() is ajragmentary side elevation showing the aa-instable .immune ein@ are parigi means which are engaged by a movable cani 'track for changing the adjustment of the die during the movement of the sheet through the die;

Fig. 11 is a View similar to Fig. 3 of a simplil'ied form of my apparatus showing incorporated therein the drag exerting and guiding mechanism shown in Fig. 9;

Fig. 12 is a transverse section taken substantially on the line |2-I2 of Fig. 11;

Fig. 13 is a fragmentary elevational view as viewed from the'p'osition indicated by the line I3-l3 of Fig. 1I; l

Fig. 14 is a plan view of another form of guiding means for guiding the sheetl into the irst Fig. 15 is a longitudinal section taken substantially on the line l-l5 of Fig. 11;

Fig. 16 is a fragmentary viewpartiallyin section showing still another means for exerting a drag upon the sheet as it is pulled through the dies;

s Fig. 17 is a perspective view of the lower part of the rstdie;

Fig.r 18.is a fragmentary .perspective of the upper portion of therst die;` ,i Y Y.

Fig. 19 is a fragmentary transverseV section showingstill another form of my apparatus;

Fig. 20 is a fragmentaryflongitudinal section taken on the line 2li-20 of- Fig. 19;

Fig. 21 is a perspective `view of a metal sheet showing how it is stamped and formed as it passes through the dies and over the working edges illustrated in Fig. 20;

Fig. 22 is an enlarged fragmentary longitudinal section through a pair of dies such as could be used to form the sheet shown in Fig. 21. In this view the rst die is not mounted for angular adjustment in the manner illustrated in the preceding views;

Fig. 23 is a view similar to Fig. 22 showing a slightly diierent construction of the dies and illustrating the manner in which the removable and replaceable inserts may be used where the most wear occurs;

Fig. 24 is a view similar to-Fig..22 showing a still diierent construction and arrangement of the dies;

Figs. 25, 26 and 27 are perspective views of three different sheets in all vof which the longitudinal stretching throughout the width oi the sheet was the same and in which the differential stretching throughout the thickness of the sheet in each of the forms was different;

Fig. 28 is an enlarged longitudinalV section through a pair ofdies, one of which is iiexible, illustrating the manner in which the flexible die is mounted in the apparatus;

Fig. 29 isan enlarged transverse sectional view through one of the cam tracks in the lower end of the cooperating push rods through which the geometrical shape and Vthe vertical position of the flexible dies is controlled;

Fig. 30 is a longitudinal section takenron the line 30-30 of Fig. 29; A y

Fig. 31 is a fragmentary section taken on the line 3I-3l of Fig. 30; y Y

Fig. V32 is a fragmentary sectional side elevation of the lower end of a "diierent form of the push rod assembly;

Fig. 33 is a fragmentary central longitudinal section through still another arrangement of dies and the operating mechanism therefor;

Fig. 34 is a fragmentary perspective view of a metal sheet showingthe form it takes and how it is bent as it passes through the dies illustrated in.Fig. 33; c.

Fig. 35 is a perspective view of an inverted boat jig covered by a transversely slitted plane sheet showing the diiferent surface areas which must be imparted to the sheet at the various stations to form the boat illustrated;

Fig. 36 shows a series of transverse sections through a sheet taken just after it has been drawn over the second Working edge which cooperates with the iirst working edge to impart the differential longitudinal stretching tov the sheet. These sections correspond to the various stations indicated in Fig. 35;

Fig. 37 is a View looking into the discharge end of a die constructed for simultaneously forming a plurality of identical sheets;

Fig. 38 is a view similar to Fig. 37 showing a die for simultaneously forming a plurality of diiferently curved sheets;

Fig. 39 is a View similar to Figs. 37 and 38 showing a die forming a series of reinforcing ribs through the sheet as it is being formed; v Fig 40 is a perspective view of the sheet which has been formed with my apparatus;

Fig. 41'is a view similar to Figs. 37, 38 and 39 showing the construction of one of the dies used in forming the sheet illustrated-in Fig. 40; and

Fig. 42 is a perspective view of another sheet which has been formed by my apparatus.

lIn forming sheets,having a desired compound curvature therein, according to my process with the apparatus disclosed herein the sheet is pulled through a plurality of slotted dies each of which has incorporated therein a working edge over which the sheet is bent in rst one direction and then in the reverse direction. The working edges which are of diierent geometrical shape are disposed in stepped relation with respect to the movement of the sheet, and are arranged to successively engage the sheet on opposite sides thereoi. Some of the dies and the working edges therein cooperate with each other to differentially stretch the sheet longitudinally throughout its width. This differential longitudinal stretching imparts a predetermined change in surface area to the sheet which is dependent upon the diie'rence in geometrical shape of the working edges and their relative positions with respect to each other.

The last die and the workin-g edge therein functions to diierentially stretch the sheet throughparted to the sheet, both longitudinal and transverse. The diesare all adjustably mounted and means are provided for changing the relative position of the dies, and their working edges, to each other during the movement of the sheet through the dies. Means are also provided which engage the sheet and act to retard its movement through thedire, Vor vexert a drag thereon. yThis drag is necessary to the longitudinal stretching of the sheet, for if the sheet was permitted to :be pulled freely through the dies there would be no longitudinal stretching. This drag is exerted in several ways. One is by the bending of the sheet over the working edges, especially the working edge in the first die; another is by the frictional engagement of the sheet between the cooperating sections of the dies, and still another is by independent means which are arranged to engage and/or grip the sheet and ,act to retard its movement Y `The rst dials mounted ior longitudinal moverv ment, and ier angular adjustment about an axis which is substantie-1hr coincident with the wort:-4 ing edge therein. This double adiustment or the rst die accomplishes two things. it varies the angleA at which the sheet is bent over the working edge therein which varies the drag exert.- ed on the sheet. the more acute the angle the greater the drag; and second it varies the distance between the rst and second working edges which will vary the amount the sheet is longitudinally stretched between these two edges, the. greater the distance the less the. stretch and vico versa.

The other dies are mounted for movement. both transversely to and perpendicularly to the mov-e ment of the sheet. Aliso the. geometrical shape of any or all oi the working edges, except the first, may be changed. Any or all or the various adjustments may beV fixed or they may be varied as desired, while. the sheet. is being pulled through the dies, by cam tracks which are moved in timed relation to the movement of the sheet. With this arrangmnent it is possible to vary both the longitudinal stretchingand the differential stretching throughout the thickness or a sheet as desi-red while the sheet is being pulled through the dies, and in this manner impart to the sheet anyy desired pair of principal curvatures at any point.

As shown in Figs. 2 and 8 the base l is rigidly secured to a bed lo'. along which a slide 2 having grooved sliding surfaces 3 is moved. The slide 2 is power driven by any conventicna1 means and travels. along the 4bed to in the direction of the arrow when drawing a sheet through the machine. Mounted on the slideY 2 isa standard 4 to which adjusting blocks 5 are rotatably mounted by studs 6. Clamps I are operatively secured to the blocks by spring straps S, lugs it and adjusting screws 1. The clamps l0 have serrated jaws l2 between which the forward end of a sheet I3 is clamped by screws It. i

The standard 4 has a keyway f4? and keys l5 for mounting adjustable: and interchangeable cam units. numbered generally as i6 to 26 inclusive, which will be described` later.

Cores 281 and drains 21 in the base I (Fig. 5) collect the surplus lubricant used', as will hereinafter be described, from whence itis pumped, cleaned and ive-used.

A slide 30, comprising a rigid U-shaped member is slidably mounted, for transverse movement, on the base l by' gibs 3l. This slide carries all of the dies, as will be hereinafter described, exceptthe Erst die.

. A second slide 32 on which the first die mechanism is mounted, is slidably mounted on the base Il for longitudinallk movement towards and away from the cross slide 3l?k and' is guided by gibs 33 (Fig. 5). To controly the movement and position of the slide 32', there is provided a toggle link construction as best showin iny Figs. It and 8'. The toggle construction` consists of a pair of links 3ftV which are pivotallyf connected to links 35 and 36 respectively. They rear ends oflinles 35 and 3E are pivotally connectedto rearward extensions 29 on the base I and the forward ends ofV the links 34 are pivotally connected tov a bar 39; adjustably secured: to: the slide 32; rl'heA purpose of the bar 39 is to adjustthe positionv of the slide 32 which is done by the setscrews 40 and clamping serewstltl` A cross link 42; connects. the pivotal-ly cormectedends: of links. 34. and 35-l to thefprvotallyconnected ends: of links 34 33, Av link 36, pivotally connected to an extension 29 on the base t, has an arm 31 to which a socketed handle. 38, for manually importing angular movement to the toggles .is attached. Thus, by operating handle 38, the links mayfbe moved from an irl-line po,- sition,.as shown in Fig. '1, into an angular relation, thereby retracting the slide 32. The slide 32 may also beimoved by motion imparted to an extension i3 which is rigidly attached to the cross link d2; The end of the extension 43 supports cam rollers 44 which are in constant contact with a cam member 45 adjustably attached to the cam plate 25. The cam plate 25 is moved by the slide 2 to which it is secured. The cam member 45 is held and adjusted by means of screws 41 engaging the plate 25 through slots 46. The slide 32 may also be moved .by motion imparted to arm extension 33 (Fig. 11) actuated by an hydraulic cylinder |84 Ahereinafter described or by other means.

A A transversely extending platform 48 is secured to the slide 32, in spaced relation thereto, by legs 49 at each fend thereof, and bolts 5a, An up wardly extendingl standard 5t is secured to each end of the platform 48 by bolts 53 passing through flange 52 formed integral with the lower ends of the standards 5l. The standards 5l have arcuate grooves54 formed on their inner faces, and have slots 55 adjacent to and concentric with the grooves 54.A

-The first die Dl comprises lower and upper parts 55 and 51 respectively which are adjustably held in spaced relation to each other so as t0. define a passageway or throat 82 therebetween through which the Vsheet is pulled. The lower and upper parts 5E and 51v have seatsl 63 and 59a, respectively, as shown in Figs. 17 and 18, in which changeable inserts and 8| (Fig. 8) areremovably' secured. The forward edge of the insert 80 or of the insert 8| is the working edge of die throat 82 according to the angular position-of the parts 56 and 51 and their position as a unit relative to a second die throat 83.

' The lower part 53 has secured thereto at each end thereof an end-plate 58', each of which has formedon its outer face an arcuate rib 55 which has the same radii; as the grooves 54, and whose common center is substantially coincident with the forward opposed edges of the inserts, (lll and'l.

` The die Dl'is mounted between the standards 5lv for angular adjustment about auv axis substantially coincident with the working edgetherein, by means of the ribs. 59 on the outer faces of the end-'plates 58 andthe cooperating grooves 54 onV the inner faces of the standards 5l. The die. may be heldv in any desired adjustment by clampingbolts 52 which are. screwed into tapped holes 62a in the end-plates 5a, and are adapted to ride inthe slots 55.

Y Ihe angular adjustment of the-die Bhowever, may be changed automatically as the Sheet I3. passes through it (when screws 62 are loosened) bythe action of an adjustable cam 24 `contacti'ng al roller 1d (Figs. 5 and l0). The roller llt ismounted on an adjustable block. 15 which may be rigidly clamped at. anyl desired point along the length ofv a pivoted lever arm 15. One end of lever arm 15 is mounted Von pin 11! fitted' into boss 18;.on standard' 5t. A turnbuckle linltl 19 is, pivotallyy connected to the free end of the `arm 'tti andi tota, pin 5t projectingv from a boss 60- on thefpl'ate' 58'. The cam 24 is adjusted vertically in a; frame 24a along its lengthl by screws 245 engaging the cam 254- and threaded* anchor' blocks 24e in the frame 24a, which frame is supported at intervals on bed Ia.

The upper part 51 of the die D1 (Fig. 15) is held in position relative to the lower part 56 by means of pins 6I engaging elongated holes 61 in ears 66 at the ends of the lower part 51. The elongated holes 61 when engaged by pins 6I allow a vertical play between parts 51 and 56 and also provide a hinge to separate the parts for purposes of repair or inspection (see dotted lines 51a of Fig. 8), or for the fast loading of sheets on production runs by a partial separation of the units.

The upper part 51 is spaced from the lower part 56 by set-screws 13 and is rigidly clamped in position by screws 14 passing freely through holes 63 (Fig. 17) and into tapped holes 68 (Fig. 8).

The parts 56 and 51 have cores 85 for lightening their weight and for containing a lubricant for the sheet I3. As best shown in Figs. 9, 17, 18 and 24, oil may be delivered from the cores 85 under pressure to oil holes 1I by backing out setscrew plugs 81, and through oil holes 65 when the screw plugs 88 are removed.

The purpose of the oil plugs 81 and 88 is to localize the oil ilow laterally to the regions where the sheet metal I3 passes, since a variety of widths of sheets may be drawn. The cores 85 receive oil under pressure through a pipe tting 86 which is connected to an oil pump by exible means (not shown). Fig. 18 shows oil grooves 18 on the surface of guide plate 51 that lubricate the entire surfaces of the sheet as it passes between the parts 5B and 51.

The outer ends oi" the oil holes 65 in the construction Vshown in Fig. 24 are threaded to receive oil plugs 88 which when removed allow oil to flow through holes 89 and grooves 89a in inserts 88 and 8|.

Fig. 9 shows the die D1 adjusted so a-s to decrease the amount the sheet is bent over the working edge therein as it is being pulled through the die. This decreases the force acting to retard the movement of the sheet. In other words it decreases the drag on the sheet.

As has been previously stated, the change in the angular adjustment of the die D1 and the die throat 82 increases or decreases the retarding force on sheet I3, which force is necessary in the longitudinal stretching and working of the sheet I3 between the throats 82 and 83. This retarding force is created at the discharge end of the throat 82 by virtue of the stiiness of the metal sheet I3 resisting deformation and is greater when the sheet is bent at a relatively sharper angle than when bent at a lesser angle. It has been found that the radius of the bend of the sheet at the throats may be as short as two to six times the thickness of the metal. However, larger radii may be desirable: and still provide suflicient retarding force necessary to work the metal between die throats 82 and 83.

It has also been found that when the radius of curvature of the working edge of the die throat insert over which the sheet I3 bends is relatively large, the pressure per square inch of the sheet is relatively small and the danger of lubrication failure between the sheet and bending edge is reduced because the bending force created at a bend having a relatively large radius of curvature is less than over a sharper bend and also the metal being bent covers a larger area over which a smaller force is distributed. The radius of curvature of the bends 0f the .sheet I3. however,

8 is such that the sheet is stretched beyond its elastic limit. Details of different working edges and throat inserts will be described later.

The adjustment of the set-screws 13 and 14 to change the distance-between the parts 56 and 51 and hence vary the pressure on the sheet I3 is another method or controlling this retarding force. However, inmost cases, this practice is not desirable because the surfaces of the sheet would perhaps be damaged due to abrasion, and variations in the thickness of the metal would cause fluctuations ofthe retarding force. With the proper distance between the parts 56 and 51 a heavy grade of lubricating oil applied to the sheet as previously described may substantially increase the retarding force.

The guiding surfaces of the parts 56a and 51a (Fig. 4) may have curved complementary surfaces to increase the retarding force necessary for Working sheets of certain physical characteristics,

In Figs. 9 and 11 is shown another auxiliary means for creating and applying a retarding force to the sheet I3. A guide bar 98 issupported at its ends by rotatable arms 33 which are pivoted on pins 94. The pins 94 are set in bosses 91 on the part 56. Adjustment of the bar 98 is had by moving clamping screws 96 which are threaded through lugs on the rotatable arms 93 and engage the part 58. By moving the bar 98 upward, say to the position 88a (shown in dotted lines) the sheet I3 is forced to follow a path I3a (shown in dotted lines) in which path it engages the entering edge of upper part 51 at an angle. Likewise, the sheet I3 may be led under the guide bar 98 and the position of the guide bar 98 be adjusted to force the sheet against the entering edge of the part 5E.

Still another means for applying a retarding force to the sheet I3 is shown in Fig. 16. To the trailing end of the sheet. I3 is attached a clamp 98 which is connected to a rod I 82 to which a retarding force may be applied by any well known means such as weights, springs, or friction blocks (not shown). Release of the sheet I3 may be automatically had as the end of the sheet approaches the die D1 by mounting a bumper |88 and a set-screw I8I on the lower part 56 so that the tripping lever 9S of the clamp 98 strikes the screw I8I before the clamp l98 strik-es the die D1. The clamp 88 is carried by a slide I83, shown in dash and dot lines, which is slidably mounted on the bed Ia in a manner similar to the mounting of the slide 2.

It has been found in practice that the preferable methodof regulating the retarding force applied to sheet I3 isthe angular adjustment of the die D1 which adjustment defines the angle at which the sheet I 3 is bent over the working edge of the throat 82. Not only is the construction simple, but it is economical in sheet metal since the retarding force remains effective to the very end of the drawing of the sheet whereas with the use of the other retarding means the retarding effect diminishes or ceases when several inches of the end of the sheet still remain unworked behind the die throat 82. v

The construction of the several forms of the second die and the working edges therein and the operating mechanism therefor will now be described. .Y

As shown in Figs. 3, 5 and 8, there is provided a frame |84 which is rigidly Xed to the cross slide 38- by means of screws III) passing through slots III, in tbecross .slide 38 and by gibsA IIZ rig-idly secured lto the/cross slide 30. The frame 104 :has guidesior push vrods I ll-8, H9 and |20 and I'sleeves |24, |22, A|23 and |24, fand has heel extensions |08 and 109 engaging the discharge side Aof a second die D2 to take up `the longitudinal thrust exerted thereby, which is created 'by the deformation Vof rthe Sheet |3 as it is -d-rawn through the throat.

rlhe frame HlLalso takes up the thrust lcreated at the guide surface f|=01 by the operation of the rigid throat| release |actuating mechanism described hereinafter,

Geshape'd frames il 3, I4, It fan-d 1-l6, mounted in planesat rig-ht angles to the direction of move;v ment -of the lsheet, are rigidly secured a-t -their lower `ends to flanges on the push rods H1, H3, ||9 and |20, respectively, and have secured to their 'upper ends sleeves |2|, `|22, |23' and |24, respectively., the push rods and sleeves being 'guided in holes and |06, respectively, in frame |04. As best shown .in 5 and 8 the upper `ends of fthejpush rods H1 to 420 inclusive are-threaded for adjusting nuts 125.

. The adjusting nuts have at 'one fend spherical surfaces |26 and |21 which are concentric. Piercing these spherical 'surfaces is 'a clearance vhole |218 through which a shouldered screw `|29 may concentrically pivot against sur-face |21 of nut |25 by virtue of its spherical surface |30. The shoulder' 13| of the Yscrew |29 rests' tightly on a swivel uut |32 also havingr a Spherical surface l 33 concentric with surface |226 of nut |25. A sliding clearance is provided between the surfaces |30 and |33 for thev swivel action 'oi' thenut |32 which has a threaded end |34 for screwing into a supporting dovetai-l grooved block.v |35. The dovetail groove or the block |35 supports and slides on `the outer dovetailed flexible strip |36 which 'supports the die throat 'working elements I 31 and |38 of which several types will'b'e described later in connection with Figs. 22, 23, 24 and 33.

The upper nexb-le die throat working element |38 is supported in a manner similar to that of lthe lower element |3't just described. The swivel nuts 132s have their threaded lends screwed into f supporting dovetail grooved block |35a and the adjusting nuts |25a are screwed onto the lower threadedeatremity ci stems |39, |40, |4| and |42, respectively. which are mounted with a sliding nt in siceves fzl, |22, |23 anu |24, respectively.'

Directly above sleevesA |2| to |24, inclusive, are bent 'extensions |43 having* pivot pins |44 therein and having vsshaped clearance stops |45. The upper extremities of the stems |39 to |42, inclusive, are also provided with pivoting pins |46. Toggle links |47 and |48 are pivotally connected together by 'pins |49. Links |41 are pivota'lly connected to pins |44 and links |43 arev pivotally connected to lpuis |46. 'Ilhe pins |49 extend latorally from the sides of toggle-links |48 and 'nt lslidably intovertical slots |50 in actuating bars l5 l The actuating bars i5 i-slide on the surfaces 1|Gl of the framework |04 and may cooperated manually or by any other well known means.

Fig. 6 shows'one' extremity of bars |5| being con- 10 ber |38 in constant spaced relation `'to the lower flexible die throat' -supportingvmember |31.

In loadinga new sheet |3 ior delivery to the jaws of the clamp 1| 0, the fgapbetween the yflexible die throat members should rbe opened for quick and easy passage of the sheet to the clamps |v0. This is accomplished by the hydraulic pis-ton |52, or other means, moving actuating .bars |5| so that -p-ins '|49 `force thctoggle links |41 and|148 to collapse vand thereby'raise4 theste-ms |33, |40, i4! and |42. 'Iheslots |50 allow lfor a uniformly spaced gap to be opened between the flexible die throat members |31' and |38, regardless of the curve that these; `unitsmay be forced to assume by the independent Iaction of the adjustable cams le to 23, inclusive.

At thebase of push rods-1 H0, H9 and |20, rollers |54 are mounted which ride on the ad- ,instable surfaces, respectively, of the cams IB to V23, inclusive. Contact with these surfaces is vassured by compression springs 55- inserted bejtween flange extensions "|56 on the .pushrods |1, H8, M9 and |20 and thev upper ends 'of spring pockets |51 in the frame .404. l

'Ihe adjustable cams I6.. to 23, inclusive,v are ier the purpose ofrmoving tothedesired instantaneous positions the various stations of the die throat Y83 relative to the corresponding stations of die throat 32. -By the individual adjustment 'oi these camsuriaces an Ainfinite variety of shapes may be produced and duplicated economically for either individual ormass production. Further- 'roora once each cam-isset according to calcula` tions or set to positions determined from graphs or tables for aparticular material and shape,

the setting of the cams to repeat thev shape at some Afuture timeis Aeasily accoritplished by keeping records :of positions of the cam setting screws of each production My'apparatus may be supplied with two kor more `sets of cams IS to 23,` inclusive, and adjustingscrews so that Vone -set may be adjusted A to produce a certain shape of drawn sheets while the machine is being used to produce-another sliapc' oi drawn sheets.V Each cam may be adjusted by graduations from predetermined gures or by matching the prole of the camto-a predeterminedd paper graph. 'In making'such adjustments each cam or s et of cams may 'be in position in the machine orthey may be on a bench nearby., B y this method, interruptions' in the constant flow of .production by the machine reduced to a :minimum, sincerthe sets of cams I6 to 23', inclusive, may be interchanged in a few minutes. Y

The heights of the working s'riaces |58 of the cains are adjustedrby setting the positions of the adjusting set-.screws s best shown in enlarged view Fig. 29, the 'set-,screws |50 are retained at one end by a dovetailed block ll which nts into the lower dovetail grooved flexible blade |52 which tetil with ther olpoht blades ||3.and |64 fi'l a l'iblebit 'Settable cam, the' working suiace.` :A |58 of which operate "the flexible throat push rods., since the surfaces |53 at times assumeinclid curved surfaces, the

Vadjusting screws to be always normal to this sur- :l1 working surface |59`which surface is independently adjustable relative to the surface |58 by screws |59a and |5912 so that relative motions of pairs of push rods may be obtained from the two surfaces. The purpose of this action will be described later.

Figs. 11, 12 and 15 show the principal elements of fone embodiment of my invention just described, but in these figures is disclosed a simplified arrangement for adjusting the positions of the various stations of the adjustable second die throat 83. The forming elements of die throat 83 are similar to those shown in Figs. 3, 5 and 8, and they are adjustableby nuts |25 which are screwed to studs |69. The studs |69 are spaced similarly to the push rods ||1 to |28, inclusive, but are held rigidly in an interchangeable lower adapter and an interchangeable upper ram |1|. The adjusting nuts |25 in this case serve to produce the desired contour of the die throat 83, as best viewed in Fig. 12.

The lower adapter |18 is rigidly fixed to the cross slide 30. 'Ihe upper ram |1| is slidably mounted on the cross slide 30 and is held in place by gibs ||2. Vertical sliding motion of the ram |1| is obtained by pivotally connected toggle links :|12, |13 and |14. The lower links |12 have their lower ends pivotally connected to the ends of the ram |1| and have their upper ends pivotally connected to the toggle links |13 and |14, respectively. The pivoting points of the toggle links are connected by a tie-bar in order to produce related motion of the two sets of toggles.

The upper pivoting points of links |13 and |14 are pivotally supported by adjustable brackets |11 and |18, respectively, which are fastened to the uprights of the cross slide 30 by screws |||l which pass through slots in the cross slide 30. Screws |19 in the upper ends of the uprights of the cross slide 30 rigidly locate the proper height of ram 1| when the toggle links |12 and |13 and |14 are in line position.

At the bottom of the ends of ram l1 I, surfaces are provided to contact adjustable stop screws |80 supported at the ends of the adapter `|1|l for the purpose of maintaining the proper clearance in the die throat `|334. I

To load a sheet I3 in the machine and to clamp it by the jaws |2 (Fig. 8), the ram is lifted by collapsing the toggle links |12, |13 and |14 from an in-line position (Fig. 12) to a position such as shown in Fig. 13. The` links |13 may be provided with an extension arm |13a for inserting a handle similar to' socket handle 38 (Fig. 3) for manually operating the ram. The ram Vmay also be mechanically or hydraulically operated by providing the link |14 with an extension arm |116 shown in dotted lines in Fig. 12 and moving it by a hydraulic piston in a cylinder |84, shown in dotted lines.

Referring particularly to Fig. 12, the cross slide 30 is moved transversely by a cam unit similar to cam previously described. A cam plate 26 is slidably supported by the base I, as is the cam plate 25, and carries an adjustable cam track |82 which isengaged by rollers |8I. The rollers |8| are carried by an extension |8|a which extends outwardly from thecross slide 3|).

The effect of moving thefcross slide 38 during the drawing of the sheet I3 through the machine and with the slide 32 stationary throughout the draw, is to shift the areas of maximum and minimum stretch laterally in accordance with the relative lateral movement of the Vcross slide 30.

' In Fig. 42 is illustrated the product of such a method of drawing a sheet. Without the lateral shifting of the cross slide 38 during the draw, the high longitudinal section of the sheet, or wherel the metal has been stretched the most, would have followed the center line B of the sheet, but by shifting the cross slide laterally first to one side and then to the other side of the center line of the machine, the high section of the sheet has been shifted to one Side of the center line of the sheet and then to the other side, as indicated by the line A. Complicated or diiiicult shapes are thus formed by the cross slide action of the second die D2. It is at once obvious that further complicated shapes may be formed by simultaneously moving the slide 32 during the draw.

In Figs. 19 and 20 is shown another modification of my apparatus of the pulsating second die throat type. The differences between the construction shown in these figures and that shown in Figs. 3, 5 and 8 are that the die throat 83 receives positive movements of its lower forming element by cam action already described in connection with Figs'. 3, 5 and 8, but the upper forming element is provided with spring take-ups and the sheet |`3 itself .determines the separation between the working edges and the guide surfaces within the die throat 83.

Referring to Figs. 19 and 20, the toggle links |12, |13 and |14 support a ram |85 which is guided, adjusted and lifted similarly to ram |1| previously described. The ram contains bores for plungers |86 and springs |81. The compressional forces exerted by springs |81 are adjusted lby threaded plugs |88. The plungers |86 support the Vflexible die throat supporting member |38 as has been described in other cases. The push rods |89, |90, |'9| and |92 are moved by cams in the same manner as push rods ||1, H8, ||9 and |28 (Fig. 5).

In practice it has been found unnecessary to provide guide blocks to keep the sheet from moving laterally during the draw when there is no cross motion of the cross slide 30 or when the sheet is in the form of a rectangle.

One construction for guiding the sheet |3 having parallel sides against sidewise movement is illustrated in Figs. 9 and 11. Guide blocks 9| are positioned along the guide bar 90 and fixed in position on bar 90 by set-screws 92.

When the sheets to be drawn are trimmed blanks of a symmetrical form and guiding is necessary, adjustable guide blocks are provided, as shown in Fig. 14.-. Two guide blocks i| 93 are slidably mounted on a support bar |94. These blocks are clamped to a cable by screws |96. The cable |95 runs over pulleys |91 at the ends of bar |94 which pulleys lare forced under the tension of springs (not shown) outwardly which creates a tendency to bring guide blocks |93 towards the center of sheet |3.

As previously stated, the effect of stretching unequally the various longitudinal portions of the sheet is to increase the areas of certain portions and by controlling the stretching in the sheet throughout its thickness after the areas have been formed by stretching between the stretching throats a proportional part of the effect of increased areas is controlled to cause a longitudinal curvature and the remainder of the effect of increased larea will manifest itself in a transverse curvature.

Referring particularly to the enlarged view of my second die throat'in Figs. 22, 23 and 24, the

wards each other as the sheet is drawn through the machine, that is, the distancesbetween Corresponding stations of both edges are uniformly increased or decreased, therewill occur an incidental increase o1' decrease inl the stretching in the longitudinal portions which will be independent of the unequal stretching of the longitudinal portions due to the diierences in .curvatures-of the two stretching working edges. WhetherY this incidental stretching is uniform transversely of v.the sheet will be determined by the uniformity ofthe distances between corresponding stations of the two edges. When the curvatureY control working edge and the second stretching workingedge are moved nonuniiormly to each other, the incidental stretching will be non-uniform transversely of the sheet. The effect of this incidental stretching is taken into consideration in setting the iiexible cams that determine the relative motion between such edges. Advantage is taken of this eiect to obtain particular results. such as, Vfor example, a sheet that changes in curvature abruptly along its length from a predominatingtransverse curve to a predominating longitudinal curve orv that changes from a longitudinal or transverse curvature in one direction to a curvature'in the opposite direction. i

Referring to Fig. 21 there is shown therein the form that the sheet I3 assumes as it is being drawn through a machine having iirst and second throats arranged as shown in Fig. 22. The sheet I3 at station Z-Z is at, as the section of the sheet i3 at that station has not been subject to any stretching. The sheet l'at station Y-Y is being worked over the working edge of the rst throat (arrow 2li), Fig. 22) of a sharpness or having a radius of curvature as Vdictated by the thickness and physical characteristics of the metal. The sheet I3 at station X-X is being worked over the working edge of the vsec.- ond throat (arrow 2l l and it is being unequally stretched longitudinally between stations Y-Y' and X-X' as indicated by they diierences'in length of longitudinal lines X-Y, M-N, U-V, M'N and X'-Y. The sheet at station :W-W' is passing over the curvature control edge '(arrow 212) where the nal curvature ofthe sheet is fixed. It has been found in drawing sheets ofimetal through my machine that when one longitudinal portion (say, the central portion) is being stretched, reactions are set up in other longi-L tudinal portions (near the edges) due to the metal in the portions adjusting itself to the drawing conditions of the central longitudinal portion being extended in area but with the front edge of the central `portion of the sheet being moved forward at the same rate as the edge portions. There is therefore a tendency under those conditions for the edge portions between the stretching throats to be formed into waves. To" overcome this tendency, the surfaces adjacent the stretching working edges (see Figs. 22, 24 and 23) are extended to form a confined passage fol the sheet so that such portions of the sheet under such drawing conditions are compressed.v This permits of obtaining eXtreme curvatures by conservative stretching because the eiect of the compression inrone longitudinal portion is additive `to the effect of stretchingin another longitudinal portion.

It is of course understoodv that variousmodiflcatlons of my invention-will be apparent to those skilled in the art in the adaptation of my invention to particular problems insheet forming that come within the scope of the appended claims.

I claim:

l. In a sheet metal working apparatus for imparting transverse and longitudinal curvatures to a sheet, a pair of slotted dies through which the sheet is successively pulled and which have each a working edge, the said working edges being of substantially different longitudinal contour and disposed in stepped relation with respect to the movement of the sheet and arranged to direct thev sheet as it is pulled through the dies so that the sheet is successively engaged on opposite faces bythe working edges and is abruptly -bent over the working edges first in one direction and then in the reverse direction and retarding means operative to en-gage the sheet ahead of the dies and impose a drag upon it, whereby the sheet is diierentially stretched throughout its width as it is pulled through the dies.

2. In a sheet metal working apparatus for imparting transverse and longitudinal curvatures to a sheet, a pair of slotted dies through which the sheet is successively pulled and vwhich have each a working edge, the said working edges being of substantially different longitudinal contour land disposed in stepped relation with respect to the movement of the sheet and arranged to successively engage the sheet on opposite faces land cooperative to bend the sheet abruptly in rst one direction and then in the reverse direction, means immediately associated with the working edges for directing and constraining the sheet to said engagement with the working edges asv the sheet is pulled through the dies and retarding means operative to engage the sheet ahead of the dies and impose a drag upon it, whereby the sheet is differentially stretched throughout its width as it is pulled through the dies.

3. In a sheet metal working apparatus for imparting transverse and longitudinal curvatures toa sheet, a plurality of slotted dies through wl'iich the sheet is successively pulled and which have each a working edge, said Working edges being in stepped relation and ofV substantially dierent longitudinal contour and arranged to 'successively engage opposite faces of the sheet as it is pulled through said dies, one of said dies being mounted for angular adjustment about an axis -substantially coincident with the working edge therein, and means for effecting said adjustment whereby the angle at which the sheet is pulled over the working edge is changed and the resistance acting to effect a drag upon the sheet which is created by drawing the sheet over the working edge is varied.

4. In a sheet metal Working apparatus for imparting transverse and longitudinal curvatures to a sheet, a pair of adjustably mounted slotted dies through which the sheet is successively pulled and which have each a -Working edge, the said working edges being of substantially different longitudinal contour and disposed in stepped relation with respect to the movement of the sheet and arranged to successively eng-age the sheet Von opposite faces and cooperative to bend the sheet abruptly in rst one direction and then in the reverse direction, means for changing the relative position of said dies with respect to each other while the sheet is being pulled through said dies and retarding means operative to eng-age the sheet ahead of the dies and impose a drag `upon it,:whereby the sheet is differentially stretched Ythroughout its width as it is pulled through the dies.

5. In a sheet metal Working apparatus for imparting transverse and longitudinal curvatures to a sheet, a pair of adjustably mounted slotted dies through which lthe sheet is successively 4pulled and which have each a working edge, the said Working edges being of substantially different longitudinal contour and disposed in stepped relation with respect to the movement of the sheet and arranged to successively engage the sheet on opposite faces and cooperative to bend the sheet abruptly in rst one direction and then in the reverse direction, means cooperating with the rst die to exert a drag upon the sheet, and means for moving one of said dies in the direction of movement of the sheet While the sheet is being pulled through said dies.

6. In a. sheet metal working apparatus for impart-ing transverse and longitudinal curvatures to a sheet, a pair of adiustably mounted slotted dies through which the sheet is successively pulled and which have each a Working edge, the said Working edges being of substantially different longitudinal contour and disposed in stepped relation With respect to the movement of the sheet and arranged to successively engage the sheet on opposite faces and cooperative to bend the sheet abruptly in rst one direction and then in the reverse direction, means for moving one of said dies laterally with respect to the movement of the sheet While the sheet is being pulled through said dies and retarding means operative to engage the sheet ahead of the dies and impose a drag upon it, whereby the sheet is dierentially stretched throughout its Width as it is pulled through the dies.

'7. In a sheet metal working apparatus for imparting transverse and longitudinal curvatures t a sheet, a pair of adiustably mounted slotted ies through which the sheet is successively pulled and which have each a Working edge, the said Working edges being of substantially different longitudinal contour and disposed in stepped relation with respect to the movement of the sheet and arranged to successively engage the sheet on opposite faces and cooperative to bend the sheet abruptly in rst one direction and then in the reverse direction, means for moving one of said dies in a direction perpendicular to the movement of the sheet while the sheet is being pulled through said dies and retarding means operative to engage the sheet ahead of the dies and impose a drag upon it, whereby the sheet is differentially stretched throughout its width as it is pulled through the dies.

8. In a sheet metal Working apparatus for imparting transverse and longitudinal curvatures to a sheet, a plurality of slotted dies through which the sheet is successively pulled and which have each a working edge, said Working edges being of substantially different longitudinal contour and arranged to successively engage opposite faces of the sheet as it is pulled through said dies, one of said dies being mounted for angular adjustment about an axis substantially coincident With the Working edge therein and for linear movement in the direction of movement of the sheet, means for effecting said angular adjust.- ment, and means for effecting said linear movement as the sheet is pulled through said dies.

9. In a sheet metal Working apparatus for imparting transverse and longitudinal curvatures to a sheet, a plurality of adjustably mounted slotted dies through which the sheet is successively pulled and which `have each a working edge, the said Working edges being of substantially dif.-

18 ferent longitudinal contour and disposed in stepped relation with respect to the movement of the sheet and arranged to successively engage the sheet on opposite faces and cooperative to bend the sheet abruptly in first one direction and then in the reverse direction, means for moving one of said dies in the direction of movement of the sheet, means for moving other of said dies laterally to and perpendic-ularly to the movement of the sheet While the sheet is being pulled through said dies and retarding means operative to engage. the sheet ahead of the dies and impose a drag upon it, whereby the sheet is dierentially stretched throughout its Width as it is pulled through the dies.

10. In a sheet metal Working apparatus for imparting transverse and longitudinal curvatures to. a sheet, a pair of slotted dies through which the sheet is successively pulled and which have each a working edge, the said working edges being of substantially diierent longitudinal contour and disposed in stepped relation with respect to the movement of the sheet and arranged to successively engage the sheet on opposite faces and cooperative to bend the sheet abruptly in rst one` direction and then in the reverse direction, and means engaging the sheet and coacting with the Afirst Working edge to exert a drag on the sheet as itis pulled through the dies.

11. In a sheet metal Working apparatus for irnparting transverse and longitudinal curvatures to a sheet, a pair of dies in stepped relation to each other through which the sheet is successively pulled and which have each a non-rotatable working edge, the Working edge in the first die be-v ing non-deformable and the Working edge in the other die being deformable, and means for changing the geometrical shape of the deformable working edgev While the sheet is being pulled through said dies.

12. In a sheet metal Working apparatus for imparting transverse and longitudinal curvatures to a sheet, a pair of adjustably mounted slotted dies in stepped relation to each other through which the sheet is successively pulled and which have each a non-rotatable Working edge, the Working edge in the rst die being non-deformable and the working edge in the other die being deformable, means for changing the geometrical shape of the deformable Working edge, and means for changing the relative position oi said dies with respect to each other while the sheet is being pulled through said dies.

1,3. In a sheet metal working apparatus for imparting' transverse and longitudinal curvatures to a sheet, a pair of adjustably mounted slotted dies in stepped relation to each other through which the sheet is successively pulled and which have each a non-rotatable Working edge, the Working edge in the first die being non-deformable and the Working edge in the other die being deformable, means for changing the geometrical shape of the deformable working edge, and means for moving the said other die laterally to the movement of the sheet as the sheet is being pulled through said dies. l

14. In a sheet metal working apparatus for imparting transverse and longitudinal curvatures to a. sheet, a pair of slotted dies in stepped relation to each other through which the sheet is suc.- cessively pulled, the rst die having a straight non-deformable working edge therein and being mounted for angular` adjustment about an axis substantially coincident with the working edge therein, the other o f Said dies having a deform- 

